1. Secular Changes in the Occurrence of Subduction During the Archean.
- Author
-
Liu, Chun‐Tao, Ye, Chen‐Yang, and ZhangZhou, J.
- Subjects
- *
MACHINE learning , *ARCHAEAN , *SUBDUCTION , *SURFACE of the earth , *CRUST of the earth , *CRATONS , *BASALT - Abstract
Subduction processes play a pivotal role in facilitating material exchange between the crust and mantle, contributing to the growth of continents. However, the onset and evolution of subduction remain hotly debated. Here, we developed a high‐dimensional machine learning (ML) model to use multiple compositional data (e.g., Nb/La, Nb, Ti, Nb/U, Pb/Nd, and Nb/Th) to distinguish arc‐type from non‐arc basalts worldwide, then applied this well‐trained ML model to identify and delineate the secular occurrence of Archean arc‐type basalts. Our findings indicate that basaltic arc magmatism can be traced back to only a few early Archean cratons. A noticeable increase in the prevalence of arc‐type basalts during the Mesoarchean and Neoarchean suggests the synchronous formation of Archean subduction across different cratons. This observation hints at transitioning from the predominantly stagnant geodynamic regime to the early, more mobile tectonic regime. Plain Language Summary: Deep beneath the Earth's surface, subduction moves material from the crust to the mantle, generating magma and igneous activity. This process is crucial for building the continental crust. Despite its importance, how the subduction process evolved over billions of years remains debated. To better understand when and where subduction began, we trained a machine learning model to distinguish between arc (subduction‐related) and non‐arc (not subduction‐related) basalts to recognize the chemical "fingerprints" of subduction in these rocks. By applying the same model to ancient basalts, we could trace basaltic arc‐like magmatism back to several Archean eon cratons, known as cratons, early in Earth's history (during the Archean Eon). The number of arc‐type basalts increased during the Mesoarchean and late Archean, suggesting that subduction expanded to different regions for about 700 million years. The transition suggests a significant shift in how the Earth's crust moved and changed, from a primarily steady state to a more mobile tectonics as observed today. Our study sheds new light on the ancient history of our planet and helps us understand how the Earth's crust has evolved over billions of years. Key Points: Machine learning can accurately distinguish between arc and non‐arc basalts worldwideSubduction‐related basaltic magmatism may have produced on several cratons during the early ArcheanSubduction‐related processes may have started in cratons worldwide during the late Archean [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF